An oil, propane or natural gas furnace must "meet or exceed the highest efficiency tier (not including any advanced tier) established by the Consortium for Energy Efficiency which is in effect as of the beginning of the calendar year in which the property is placed in service."
Go to
https://cee1.org/
Then click on Resources, Residential, Heating and Cooling, Qualifying Product List.
Note that an Energy Star rating by itself is not qualifying, unless you are certain that Energy Star and the CEE are using the same standard. Also note that 97% AUFE may or may not be qualifying. If the CEE changes their ratings, the law specifies that the CEE ratings control, not a particular percentage efficiency and not Energy Star by itself.
